The First-Year Player Draft is a month away, and the Houston Astros are, as they say, on the clock.

Of course, the Astros have known they would pick No. 1 overall since the conclusion of last season, when they finished with the lowest winning percentage in Major League Baseball. So the scouting staff headed into the spring knowing it had to figure out who the top pick in the Draft should be.

There are six leading candidates to go first when the Draft begins at 7 p.m. ET on June 6, live on MLB Network and MLB.com. In alphabetical order, they are: Stanford right-hander Mark Appel, San Diego third baseman/outfielder Kris Bryant, Georgia high school outfielder Clint Frazier, Oklahoma right-hander Jonathan Gray, Indiana State lefty Sean Manaea and Georgia high school outfielder Austin Meadows.

Just what makes each of these six candidates to be selected by the Astros? And what would the knocks be that might make Houston decide to choose someone else? MLB.com went to the people who know the players best, the area scouts, and asked two questions: "Why would the player [or players] in your area make a good choice for No. 1?" and "What should be known about them that would make them a less-than-ideal choice?"

The college pitchersAppel has been here before. The Stanford ace was the potential top pick a year ago, but he ended up sliding to the Pirates at No. 8. Appel opted to return to school for his senior year and has arguably been the most consistent performer in this year's Draft class. After his win against Arizona State on Friday, he's 8-3 with a 1.56 ERA in 11 starts. In 86 1/3 innings, Appel has held opponents to a .195 batting average while allowing just 15 walks and striking out 106.

Why he should be the top pick: "He's just as good as last year, with a bit more edge to him. He has a track record of taking the ball every Friday for the past three years."

Why he shouldn't be the top pick: "Will the Astros be able to sign him this time? There have been times in the past where he's gotten hit more than he should."

Gray might be the only other prospect who has matched Appel, at least in terms of week-by-week performance. He had a no-decision against West Virginia on Friday, so his record stayed put at 8-1. Gray's ERA is 1.20. In 89 2/3 innings, the right-hander has 104 strikeouts against just 16 walks, holding hitters to a .166 batting average.

Why he should be the top pick: "The guy is 6-5, 240 pounds and touches 100 mph. I don't mean to feed you the obvious, but it's one of those circumstances, when you're picking No. 1, you look at the success he's had and the fact he's gotten better at every level he's played, it's almost a no-brainer that he enters the conversation. The conversation almost doesn't have to go more in-depth than that. There's no glaring issue with arm action or delivery. He's a great kid and comes from a great family. There really isn't anything that stands out as caution flags."

Why he shouldn't be the top pick: "If there is an unknown, he hasn't competed in summer baseball, in the Cape or [with] Team USA, as far as his exposure to a higher level of competition. This is the highest level he's thrown at, and the Big 12 isn't the best conference this year."

Manaea has the combination of pure power stuff, size and left-handedness teams often covet. He had a dominant summer season. But has Manaea shown the kind of consistency scouts like to see to be No. 1? His numbers have been good: 5-3, a 1.57 ERA, a .195 BAA in 57 1/3 innings with 72 strikeouts, though he has walked 20. A hip issue has impacted Manaea's performance lately.

Why he should be the top pick: "If he goes No. 1, it's because of what guys saw in the Cape Cod League. I've seen him for three years, and I saw him in the Cape. He hasn't done what he did in the Cape. He commanded the zone, with all three pitches, 92-96 on the fastball, the slider was plus, the changeup was plus, he was lights-out."

Why he shouldn't be the top pick: "The stuff hasn't been as consistent, the command has been inconsistent, he's had some ups and downs this spring. You saw the consistency throughout the Cape. Everybody keeps going in hoping to see what they saw in the summer, and he hasn't shown it yet. He's throwing more across his body, he's favoring it a little bit. There's some discomfort. Because he's had to adjust, the stuff hasn't been as good. He was more in line in the Cape and was very athletic. Now, he doesn't look as comfortable."

The Georgia high schoolersMeadows and Frazier. Frazier and Meadows. Depending on which scout you talk to, you'll get a different opinion about who they like better. Both appear to be sure-fire top-of-the-first-round-type players. Both are in the conversation regarding the Astros.

Why Meadows should be the top pick: "He's going to be 17 at the Draft. You've got a really young hitter. He's a pure hitter. He's one of those kids who can fall out of bed and hit. There's a lot of upside, a lot of ceiling. He has good baseball instincts, he runs the bases well. In the outfield, he's got good anticipation, his routes are advanced for a high school kid. Of the five tools, you'll have to wait for the power to come. I think it will. When that body matures, and he gets stronger, that's when the power will show up. He's too good of a hitter. He might hit .280-.300 with 20-plus home runs. That's a pretty good player. It's hard to get that, especially out of a high school kid, in the Draft."

Why Meadows shouldn't be the top pick: "I think the risk, the uncertainty, the unknown. He doesn't wow you with raw power. He'll flash some average power. You're guessing and gambling that the raw power is going to show to give you the 20 home runs. That's the risk. If he's a .300 hitter and he hits you 12 homers, that's a good player, but that's not what you want at the top of the Draft."

Why Frazier should be the top pick: "He is a dangerous hitter every time he walks into the box. He has that potential, that swing, that strength, that loft, that aggressive approach to change the game with one swing of the bat. He can hit balls out of Yellowstone Park. It's advanced high school power. Between the two, he's the closest of being a sure pick to hit you 30 home runs. With his arm, he could stay in center field, but I'd like him in right field. Runners won't take the extra base on him."

Why Frazier shouldn't be the top pick: "The downside is he might strike out 200 times. He might leave the runner on base that doesn't tie or win the game. He is a free swinger. There's potential for him to strike out a lot. He does not adjust to pitches in the strike zone. He is dead-red pull, grip it and rip it. That's his mindset, to absolutely crush the ball. That's the only plan he has when he steps in the box. He's going to thrill you and he's going to disappoint you."

The college slugger
A consistent college hitter is always going to get attention in the early stages of the Draft, which is why Moran is still in the conversation to go at or near the top. But add game-changing power and you've got a legitimate top-pick candidate. Bryant leads the nation in home runs, while also showing an ability to play both third base and right field.

Why Bryant should be the top pick: "He's a performer. He plays on the dirt and can be an absolute weapon if they moved him to the outfield. He has a game-stopping arm. He can run, he's got power. He has tools. ... There used to be too much swing-and-miss in his game, but not anymore. He has an advanced approach."

Why Bryant shouldn't be the top pick: "Someone might want to take an arm or a high school player with more upside who has comparable tools."

Jonathan Mayo is a reporter for MLB.com and writes a blog, B3. Follow @JonathanMayoB3 on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.